Production of acrylonitrile



Patented Sept. 29, 1953 ITED as s :PBQPWIIQN 9 marr w-IBM :l smae' Nlm EsHe-N- It W e e a we qli ei e i -2P same-ar ses akin-Drawing. Application July 21,1951,

' :sen lzno. 23sec;-

cat iCl-Zfikiiib My invention relates to xn nuia ture .oi acrylonitrile by the addition reaction 9! I ed lil ene and hydrogen cyanideandmore-pa ticularl relates to improvements intheicatalyticl phase reaction in which the reactants .are in! troduced into a.,mixture,oi catalytic materials in the liquid-phase.

In the manufactureof acrylonitrile using liquid phase catalysts, cuprous chlprlde'has'jbeen used as ci al sislrsi- .iiowercrrheqsiiss it 10 very limited solubility inwater, suitablefcataly'st solutions are prepared by the additionhoi ammonium chloride or alkali metal'chloridesto the cuprous salt. Due perhaps to the forniationpf double compounds, for example llI-IsCuGl large n proportions of cuprous chloride may thus" edi'ssolved. Usually lmole. oi.ammoniun1..or alkali metal chlorides has been used per mole of cuprous chloride. Particularly advantageous results have been described using potassium chlorides to a k chloride component, to! potassium 1 aan 02=mde sa hlaride per mole of cuprous chloride. 'In' general these mixed halide catalysts have been prepared in water and solutions of ab ut S SY- GBFZ, total solids are preferred.

The reaction is usually carried out at temperatures of 80-90 .C. Anexcesspr acetylene compared to hydroge cyanide is p e err dj nd pro-. portions of from 5 to lomolesot mole of hydrogen cyanidel hare be I mended. The velocity of introductionfpf hydron cyanide is i por ant and. a rate '91 .19. 9.8- ample, 1 part by Weight of hydrogencyanide per 0-50 par o fibr u h iil pe 'flhburhas been recommended. Athigher rate" t'h gen cyanide is incompletelyconverte se cya e a p ar i t ,PIQQPQtcF f e more, an excess or hydrogen cyanide acc el e tes, deterioration of the catalyst with ie;spect o" acrylonitrile formation and causes it to pro se more acetaldehyde.

Under the best conditionsnrevlously described for the operation of thisprocess; mammar pr from h reaction ans-11y statuses the following:

The cr d wa tress purification problem partly because of the nature high aisi78%.

2 theycomponentsand-'their proportions but also spe ially dueteth fn i ryius of a n jr e in p lymerization nd .cop l m i on hich esuires. n ext mel P'li e mb m r- S le fractionation of the mixture cannot be empmyed because vinylacetylene and acrylonitrile differ in boiling points by only a few degrees and because lactonitrile, boiling higher than acrylonitrile,

catalyst solution of critically higher concentrationfin terms of solids contact while maintaining vthe proportion of cuprous chloride in the catalyst serm n in excess of the other halide components that surprising improvements in yield and product distribution are developed. Previous investit op imu atalys tandpoint of both yield r .o c' i ha lin th was flreactionis a 1 t 68% I a found. howeverthatfa' e ectic exists in the sysannins aste a ch oride and lkaliv eta c lori e a, about 7 0 to 2% co ce tra on o he salts gBy opera i at all times d rin the. reaction at a concentration on the high side i t i cut "m1 avero'und t at s ificant inc eas .iii' ldl nd im o e n in pr u t distribution ,be. obtained. 1 have operated without mechanicalfdifliculty handling the catalyst during the racti'or'ior'in conducting the reaction with concentrations on the high side of the eutectic of from greater than 70% to as For example, when a, mixture of 0.8 mole of potassium chloride and 0.2 mole of sodium chloride per 1.03 to 1.10 moles of cuprous chloride made into a slurry containing 26 tol a s lutionp iiiaii inc '72 to 7. .O the ed salts is obtained on heating the mixture to above 45 to 50 C. Since this is well below the desired operating temperature of to 0., there is little, danger of solidification of the catalyst solution' provided reasonable care is taken.

Rreviousjnvestigators also have taught that an exe -s h unt il i i h c a t p i tion l' ads tothe rormation' of larger proportions of divinyfll acetylene as acontaminant of the p o u ti lhay' .i ugdll owe th t s d yl acetyle e,iqrmedii hen ex s nvi ons em ride isu s'ed-provided the concentration of the qat lysi inc ea ed-to th hi h i of the ei'it'ec'stic, i.' e.' at least alnput 72 to "741% solids. Moreover, I have found that an excess of cupr'ous chloride in the catalyst composition results in a d crease ilithe pro ort on ace aldehyde rou new: fir 'i' l v i h i -th 'ii e tration ,of cuprqus ,chloride should approximate a least about 1.03% about "1.10 mo1es or cuprous changes produced by shifting the concentration of solids content of the catalyst to the critical high side of the eutectic range and by increasning the flow of hydrogen cyanide.

cuprous chloride (CuCl) and 3.2 moles of water. The resulting mixture containing 76% of salts and 24% of water was treated with hydrazine to remove cupric copper and maintained at 80 C. while acetylene alone was passed into the catalyst solution for to minutes prior to begin- The hydrogen cyanide inlet was arranged downstream from the acetylene inlet to insure an excess of the ing the molar ratio of cuprous chloride to alkali 1O latter at all times. The hydrogen cyanide was metal halides to be in excess of equimolar, a introduced at the rate of 0.166 mole per hour per significant and entirely disproportionate increase kilogram of catalyst solution and the acetylene in conversion and yield and improvement in prodat about six to eight times this rate. uct distribution are obtained. Where previous The exit gases were passed through a series investigators have produced maximum comer-' of condensers, the first cooled with water ice to sions based on hydrogen cyanide of up to about remove the bulk of the water and the principal 80%, I usually obtain conversions averaging 5% product was collected from condensers cooled higher in the range of 85 to 90% and have obwith liquid ammonia. Several runs were carried tained conversions exceeding 90%. Where preout under these conditions with the results shown vious investigators have found side production in the following table:

Product Composition, percent Expt.No. H dr rm Acrylo- Acetal- 11,0 mtrile dehyde g g H2O Etc.

92 0.2 0.1 4 3.1 88 0.3 0.8 2.5 8.4 83 0.0 0.5 15.9 84 0.4 0.5 15.1 80 0.5 0.7 3.0 9.8 Average 87 0.4 0.5 2.1 10 Average of Runs at 65-68% catalyst concentration 80 7 2 3 8.0

of acetaldehyde and vinylacetylenes to average about 10% and side production of lactonitrile to average about 2% under best conditions, operation under the conditions of my invention results in a. crude product which is sufiiciently free of these impurities to permit purification to polymerization grade acrylonitrile by simple fractional distillation. For example, the typical composition of crude product produced by operation according to my invention in comparison to the composition set out in Table I representing averaged runs under the best conditions of conventional operation is as follows:

Table II Component Percent Acrylonitrilc 87 Aoetoldeliyda 0. 4 H g. 5 Vinylacetylcnes (mono and di) 2.1 Water 10 Total 100.0

Example I A catalyst solution was made by charging to a heated reaction pot 0.8 mole of potassium chloride, 0.2 mole of sodium chloride, 1.075 moles of The average results show distinct improvements over the previously obtainable values in increased yields of acrylonitrile and decreased proportions of other contaminants including acetaldehyde, hydrogen cyanide and vinylacetylenes.

Example II The procedure of Example I was repeated except that the catalyst consisted of 0.8 mole of potassium chloride, 0.2 mole of sodium chloride, 1.035 moles of cuprous chloride, 0.04 mole of hismuth chloride and 3.2 moles of water. The product consisted of 92% acrylonitrile, 0.5% acetaldehyde, 0.2% HCN, 1.0% of vinylacetylenes and 6.2% of water, etc.

In operation according to my invention I have found that it is advantageous to keep the catalyst in continuous use to avoid deterioration. Thus on starting up after a period of shutdown the conversion invariably seems to be less than before. Since cupric copper is known to deleteriously affect the reaction of acetylene and hydrogen cyanide to produce acrylonitrile, copper powder or other forms of copper are sometimes incorporated into the catalyst system in contact with the solution. The incorporation of elemental copper in contact with the solution, particularly in the form of copper powder, however is mechanically disadvantageous. I have found that previously described difilculties due to the formation of cupric copper in the catalyst solution can be avoided by using reagents free from air, particularly when hydrazine is used as a reducing agent to insure the absence of cupric copper in the freshly prepared catalyst solution.

I claim:

1. In the manufacture of acrylonitrile by reaction of acetylene and hydrogen cyanide at about to C. in the presence of a liquid phase catalyst comprising a mixture of cuprous chloride and alkali metal chlorides and recovery of acrylonitrile from the crude product by fractionation, the improvement which comprises reactin the acetylene and hydrogen cyanide in contact with an aqueous cuprous chloride catalyst solution which contains a concentration of total salts on the high side of the eutectic composition of at least 70 to 72% total salts and which contains at least about 1.03 moles to about 1.10 moles of cuprous chloride per mole of alkali metal chlorides.

2. The improvement of claim 1 in which the molar proportion of alkali metal chloride comprises about 0.8 mole of potassium chloride and about 0.2 mole of sodium chloride.

ROBERT M. THOMAS.

6 References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES 10 Matthews, P. B. No. 47,715, British Intelligence Objectives Sub-Committee, pp. 1-2 (1948).

Hasehe et a1., Fiat Final Report No. 836, pp. 1-9 (1946). 

1. IN THE MANUFACTURE OF ACRYLONITRILE BY REACTION OF ACETYLENE AND HYDROGEN CYANIDE AT ABOUT 80* TO 90* C. IN THE PRESENCE OF A LIQUID PHASE CATALYST COMPRISING A MIXTURE OF CUPROUS CHLORIDE AND ALKALI METAL CHLORIDES AND RECOVERY OF ACRYLONITRILE FROM THE CRUDE PRODUCT BY FRACTIONATION, THE IMPROVEMENT WHICH COMPRISES REACTING THE ACETYLENE AND HYDROGEN CYANIDE IN CONTACT WITH AN AQUEOUS CUPROUS CHLORIDE CATALYST SOLUTION WHICH CONTAINS A CONCENTRATION OF TOTAL SALTS ON THE HIGH SIDE OF THE EUTECTIC COMPOSITION OF AT LEAST 70 TO 72% TOTAL SALTS AND WHICH CONTAINS AT LEAST ABOUT 1.03 MOLES TO ABOUT 1.10 MOLES OF CUPROUS CHLORIDE PER MOLE OF ALKALI METAL CHLORIDES. 